The present invention relates to a system for determining the quality of a molded article and confirming the release of the article from the mold halves in an injection molding apparatus.
Conventional systems for confirming the release of molded articles from an injection molding apparatus have been of the photoelectric type, the electrical contact type, or the gravimeter type. Further, there are several prior art systems, such as mold monitoring systems, wherein an image of a male or movable mold half is formed on an image forming medium, a plurality of luminance sensors are arranged on this image, and by monitoring the detected luminance data, the system determines whether the molded articles are on the movable mold half or have been ejected and thus released so that no molded article remains on the movable mold half. An example of such a system is disclosed in Japanese Patent Application Publication No. 60573-1985. A system for optically monitoring only the movable mold half by a television (TV) camera or the like is disclosed in Japanese Patent Application Publication No. 4616-1983, and a system for confirming the release of an article in a molding apparatus is disclosed in Japanese Utility Model Application No. 421481-1977.
These conventional systems have disadvantages. For example, the conventional systems are complicated. They are subject to frequent failure, and their efficiency is poor. The time necessary for the injection molding apparatus to perform a molding cycle is prolonged. Productivity is thus reduced. Also, it is necessary to perform adjustments to such conventional systems each time the mold is changed.
The conventional systems have another disadvantage. The conventional systems monitor only the movable mold half and view it in only one direction. During operation of such conventional systems, it is assumed that so long as the molded article is found to be present on the movable mold half, no molding material residue remains on the stationary or female mold half. The stationary mold half, however, may be subject to damage as a result of resin leaks at the nozzle or gate of the molding apparatus or to damage due to clogging of the nozzle or gate by solidification of residual resin following, for instance, disconnection of the heater for a hot runner mold.
Another disadvantage is that the quality of the molded article cannot be determined reliably.